(1) Field of the Invention
The present invention relates to a power supply starting system, and more particularly, to a power supply starting system for starting device power units.
(2) Description of the Related Art
Power supply schemes for communications equipment include a convert-and-supply scheme wherein commercial power is received, converted, and then supplied to loads. This is a scheme for converting main power into separate power supplies of relatively small capacity. In an electronic exchange or the like, for example, DC/DC converters are used to convert a direct-current voltage, which is mainly at 48 V, to xc2x15 V, xc2x112 V, xc2x124 V, etc. to be supplied to logic elements.
Also, in a communication device constituted by a plurality of units such as an electronic exchange, the power supply system generally takes the form of a distributed power supply system in which each unit is provided with a DC/DC converter.
FIG. 6 shows the configuration of a conventional distributed power supply system. A communication device 100 comprises communication units 101 and 102 which include DC/DC converters 101a and 102a, respectively (each unit may include two or more DC/DC converters). The DC/DC converters 101a and 102a are connected to a battery 3 (commercial power etc.) via lines L1 and L2, respectively.
In this configuration, when the communication units 101 and 102 are to be started simultaneously, a simultaneous start signal K1 is supplied to the DC/DC converters 101a and 102a. In response to the simultaneous start signal K1, the DC/DC converters 101a and 102a start to convert the direct-current voltage from the battery 3 to respective required voltages and supply the same to the elements in their respective units, whereby simultaneous startup of the units is carried out.
In the above conventional distributed power supply system, however, a potential difference occurs between Vz1 and Vz2 due to the difference between the impedances Z1 and Z2 of the lines L1 and L2. If the simultaneous start signal K1 is supplied while such a potential difference exists, the DC/DC converters 101a and 102a latch up, resulting in faulty starting of the communication units. In such cases, the starting operation must be performed with the power again switched on, thus giving rise to a problem of poor quality and reliability.
The present invention was created in view of the above circumstances, and an object thereof is to provide a power supply starting system which is free from faulty starting at the time of simultaneous startup and which is thus improved in quality and reliability.
To achieve the object, there is provided a power supply starting system for starting device power units. The power supply starting system comprises a plurality of voltage converters each for transforming an input reference voltage and supplying a transformed voltage to a load element, and a start control section including simultaneous start signal generating means for generating a simultaneous start signal for simultaneously starting the voltage converters, potential difference detecting means for detecting a potential difference between the input reference voltages, and forced starting means for inactivating the simultaneous start signal if the potential difference is detected, and for forcedly starting the voltage converters after the potential difference becomes insignificant.